Introduction
Millets, deliberated as main food staples in human history, have a substantial economic impact on developing countries because of its importance as a crop at a global level.1,2 India is the world’s prominent manufacturer of millet.3 For boosting millet production as well, India celebrated National Year of Millets as 2018.4 In India barnyard millet is usually cultivated under rain fed conditions.5In which , barnyard millet agronomy is limited to hilly and semi-arid areas of Southern headland of Tamil Nadu, Andra Pradesh, Karnataka and Northern states of Jharkhand and Uttar Pradesh.6Banyard millet comparable to any other millet is nutritionally superb to cereals, so far its consumption is narrowed.3
Comparable to other cereals, millets are tremendous source of energy, carbohydrate, and protein. They remain also rich in phytochemicals and micronutrients. Phytochemicals are the naturally active organic substance of plant basis which are involved in stopping disease and upholding health. The rerun of these phytochemicals can support in recognizing the lively compounds responsible for disease avoidance due to their antioxidant and antimicrobial properties.3,7,8 Millets are recognized as nutraceuticals because of their dietary fibres, proteins, energy, minerals, vitamins and antioxidants quality that they offer for human health.9 Ingeneral millets protect health with its nutritional and nutraceutical content for a healthy living.10,7
Phytochemicals and phenolic compounds in minor millets enriches its antioxidants activity and makes it nutritionally superior to other cereals.3 Barnyard millets also known as minor millets, Japanese barnyard millet, Ooda, Oadalu,Sawan,Sanwa,and Sanwank, is a fastest multipurpose crop, which yields food and feeds in a short duration. Barnyard millet is a wonderful cereal. While equate to rice and wheat, moreover having mineral and vitamins, it is an amusing source of treasured nutrients like carbohydrates, fat, proteins, and crude fiber. In fact with delayed digestibility rate, barnyard millets have a fair source of protein with low carbohydrate content which makes it as a natural nutraceuticals food, especially for individual with high risk for non-infectious diseases such as diabetes, heart diseases, obesity, and cancer.6,11 The presence of phytochemicals, by means of phenolic acids, catechins, phytic acid, flavonoids and tannins in the barnyard millet work as noble source of natural antioxidant.12 The existence of high of amount bioactive constituents in barnyard millet thereby, recommending it as a possible healthy alternate for rice and wheat particularly for the patients with cardiac disease and diabetes .13 De-hulled varieties of barnyard millet are beneficial for Type II diabetics, due to their delayed glycaemic response.14
Even though the whole grains / unpolished of barnyard millet (without removal of bran) offer a wide range of nutrients and phytochemicals that enhance health, direct consumption of them by humans is less explored, citing the reason of delayed digestibility and acceptability, thus the present study aims at examining nutritional and nutraceutical quality of both polished and unpolished barnyard millet quantitatively.
Materials and Methods
Procurement and and Processing of Barnyard Millet Sample
Unpolished barnyard millet was procured from the local farmers and polished barnyard millet from a local shop from the city of Coimbatore, Tamil nadu, India. Barnyard millet both polished and unpolished were cleaned to remove dirt, dust, and stone. The cleaned millets (sample) were powdered and sieved using 60 mesh sieves (250 Micron). The powdered flour was stored in an airtight container at room temperature for analysis. All samples were analyzed in triplicate for quantitative analysis.
Analysis of Macronutrients Present in Both Polished and Unpolished Barnyard Millet
Quantitative analysis of both polished and unpolished barnyard millet, for their moisture (AOAC 934.01) and ash (AOAC 942.05) using gravimetric method (AOAC 942.05). Calculation of energy by proximate principle and analysis of other nutrients such as carbohydrate (uv- visible spectrophotometer,630nm), protein (kjeldahl method -AOAC 2011.11), fat ( gravimetric method – AOAC 963.15), crude fibre (gravimetric method- AOAC 962.09) and fibre including soluble, insoluble and total dietary fibre (enzymatic- gravimetric method – AOAC 991.43) was carried out using standard analytical methods – AOAC, 2016.15
Analysis of Micronutrients Present in Both Polished and Unpolished Barnyard Millet
Quantitative analysis of both polished and unpolished barnyard millet, for their micronutrients namely calcium and iron (ICP-OES method-AOAC 2011.14), vitaminC (HPLC- AOAC 2012.21) and B- complex vitamins(uv- visible spectrophotometer-AOAC 2012.10) such as thiamine (420nm), riboflavin(330nm), niacin (262nm), pantothenic acid (220nm), total B6 (716nm), biotin (348nm), total folate (540nm) was carried out using standard analytical methods -AOAC, 2016.15
Analysis of Nutraceutical Content Present in Both Polished and Unpolished Barnyard Millet
Nutraceutical content of both polished and unpolished barnyard millet was determined using standard AOAC methods 201615 for phenolic acid(550nm), phytic acid (519nm), tannin (725nm), flavonoids (510nm),saponins(435nm), alkaloids (470nm), catechins(760nm), phytosterols(625nm) by uv- visible spectrophotometer at respective wavelength. Similarly Carotenoids (450nm) and tocopherols (520nm) by colorimetric method . Also lignin( chemical oxidation and extraction method,205nm) and arabinoxylans (acid hydrolysis method,620nm).
Analysis of Starch and Individual Sugars Present in Both Polished and Unpolished Barnyard Millet
The total starch (510nm) and the reading for sugars such as fructose, glucose, sucrose and maltose was noted at a wavelength of 500 nm,540nm,340nm and 334nm respectively (AOAC 2018.01) were analysed using standard analytical methods -AOAC, 2016.15The available carbohydrate was calculated by substracting total dietary fibre from the total carbohydrate present in barnyard millet.16
The Ethical Clearance for the study was obtained from Institutional Human Ethics Committee- Avinashilingam Institute for Home Science and Higher Education for Women. (Approval No-AUW/IHEC-17-18/FSMD/FHP-02).
Data were analyzed using SPSS version 21.0. Mean, the standard deviation of all the values was calculated. The observed results were compared using Paired t-test at 99% or 95% confidence interval to indicate significance level.
Result and Discussion
Table 1: Quantitative Analysis of Macro Nutrients Present in Barnyard Millet (100g)
Serial No. | Macro nutrients | Mean of macro nutrients | p-value | |
Polished | Unpolished | |||
1 | Carbohydrate (gm) | 65.79 ± 0.02 | 68.8 ± 0.11 | <0.01a |
2 | Energy (Kcal) | 327.3 ± 0.08 | 351 ± 0.2 | <0.01a |
3 | Protein (gm) | 6.8 ± 0.08 | 10.4± 0.02 | <0.01a |
4 | Total Fat (gm) | 4.1 ± 0.16 | 3.8 ± 0.02 | >0.05c |
5 | Moisture (gm) | 9.3 ± 0.03 | 9.8 ± 0.05 | <0.01a |
6 | Ash (gm) | 0.09 ± 0.08 | 0.45 ± 0.01 | <0.05b |
7 | Soluble Fibre (gm) | 2.3 ± 0.1 | 4.4 ± 0.1 | <0.01a |
8 | Insoluble Fibre (gm) | 6.2 ± 0.11 | 9.8 ± 0.1 | <0.01a |
9 | Total Dietary Fibre (gm) | 8.5 ± 1.3 | 14.2 ± 0.28 | <0.05b |
10 | Crude Fibre (gm) | 4.5 ± 0.35 | 11.2 ± 0.08 | <0.01a |
a1percent level of significance ; b 5 percent level significance ; c not significant.
The amount of carbohydrate present in 100gm of polished and unpolished barnyard millet was found to be 65.79 ± 0.02 gm and 68.8 ± 0.11 gm respectively(Table 1). On a comparative note, the quantum of carbohydrate present in polished barnyard millet was 12.1% lesser than the milled parboiled rice and 12.45% lesser than milled raw rice.17 Similarly, the amount of carbohydrate present in unpolished barnyard millet was 6%lesser than that of brown rice. However the carbohydrate present in barnyard millet (polished and unpolished) closely concurence with that of other millets namely jowar (67.68 gm),ragi (66.82gm) ,samai (65.55gm ) ,varagu(66.19gm) and whole wheat flour(64.19 gm) thus making it a perfect a healthy choice for therapeutic use.
The protein content of unpolished barnyard millet (10.4± 0.02gm) was found to be significantly superior to polished barnyard millet(6.8 ± 0.08gm) at 1% level of significance which can be recognized to the heavy loss of protein existing in the peripheral layers of barnyard millet during the milling process. However no significant difference in the total fat content between the polished and unpolished barnyard millets were observed.
The protein content was high in the peripheral layers of milled barnyard millet, and lower in direction to the centre of kernel. The protein content was high in the peripheral layers of milled barnyard millet, and lower in direction to the centre of kernel.
Table 2: Quantitative Analysis of Micro Nutrients Present in Barnyard Millet (100g)
Serial No. | Micro nutrients | Mean of micro nutrients | p-value | |
Polished | Unpolished | |||
1 | Calcium (mg) | 24.8 ± 0.38 | 35 ± 0.10 | <0.01a |
2 | Iron (mg) | 6.2 ±0.02 | 7.1 ±0.11 | <0.01a |
3 | Thiamine (B1)- mg | 0.37 ±0.01 | 0.45 ±0.04 | <0.05b |
4 | Riboflavin (B2)- mg | 0.13 ± 0.02 | 0.14 ± 0.02 | >0.05c |
5 | Niacin (B3)- mg | 4.05 ± 0.02 | 4.08 ± 0.01 | <0.05b |
6 | Pantothenic Acid (B5)- mg | 0.22 ± 0.08 | 0.25 ±0.03 | >0.05c |
7 | Total B6 (mg) | 0.08 ± 0.01 | 0.13 ± 0.07 | >0.05c |
8 | Biotin (B7)µg | 20 ± 0.20 | 22 ± 0.16 | <0.01a |
9 | Total Folate, B9 – µg | 69 ± 0.30 | 78 ± 0.01 | <0.01a |
10 | Total Ascorbic Acid (Vitamin C) – mg | 0.11 ±0.01 | 0.06 ±0.01 | <0.01a |
a1percent level of significance ; b 5 percent level significance ; c not significant.
The analysed micro nutrients content of barnyard millet significantly varied between the polished and unpolished samples at 1% level of significance for nutrients namely calcium, iron, Biotin, total folate and total ascorbic acids. However no significant difference between the polished and unpolished barnyard millets for Riboflavin (B2), Pantothenic Acid (B5) and Total B6 was observed in the present study.
Table 3: Quantitative Analysis of Nutraceutical Contents Present in Barnyard Millet (100g)
Serial No. | Nutraceutical contents | Mean of nutraceuticals contents | p- value | |
Polished | Unpolished | |||
1 | Phenolic Acids (mg/g) | 10.30 ± 0.03 | 11.28 ± 0.03 | <0.01a |
2 | Tannins (mg/g) | 12.00 ± 0.02 | 9.78 ± 0.02 | <0.01a |
3 | Flavonoids (mg/g) | 46.20 ± 0.01 | 54.00 ±1.00 | <0.01a |
4 | Lignin (mg/g) | 7.20 ±0.02 | 6.60 ± 0.11 | <0.0a |
5 | Catechins (µg/g) | 9.20 ± 0.01 | 11.00 ± 0.05 | <0.01a |
6 | Phytic Acid (mg/g) | 0.61 ± 0.01 | 0.52 ± 0.02 | <0.05b |
7 | Phytosterols (mg/g) | 0.06 ± 0.02 | 0.05 ± 0.01 | >0.05c |
8 | Arabinoxylans ( µg/g) | 4.50 ± 0.25 | 4.20 ± 0.02 | >0.05c |
9 | Carotenoids (mg/g) | 2.56 ± 0.19 | 2.85 ± 0.02 | > 0.05c |
10 | Alkaloids (mg/g) | 5.11 ± 0.04 | 3.80 ± 0.01 | <0.01a |
11 | Saponins (mg/g) | 1.80 ± 0.10 | 2.20 ± 0.40 | > 0.05 c |
12 | Tocopherols (mg/g) | 0.08 ± 0.02 | 0.04 ± 0.03 | < 0.05 b |
a1percent level of significance ; b 5 percent level significance ; c not significant.
A significant loss (p ≤ 0.05) of nutraceutical components or secondary metabolites namely phenolic acids, flavonoids and catechins between polished and unpolished barnyard millet was observed. Polishing of barnyard millet results in loss of phytochemicals and antioxidant content present in brans.18
Table 4: Quantitative analysis of starch and individual sugars present in barnyard Millet (100g)
Serial No. | Starch and individual sugars | Mean of starch and individual sugars | p-value | |
Polished | Unpolished | |||
1 | Total Available Carbohydrate(gm) | 61.30 ± 0.04 | 57.60 ± 0.21 | <0.01a |
2 | Total Starch(gm) | 59.96 ± 0.35 | 56.80 ± 0.21 | <0.05b |
3 | Fructose (gm) | 0.25 ± 0.01 | 0.18 ± 0.01 | <0.05b |
4 | Glucose (gm) | 0.75 ± 0.01 | 0.52 ± 0.03 | <0.01a |
5 | Sucrose (gm) | 0.39 ± 0.01 | 0.10 ± 0.01 | <0.01a |
6 | Maltose (gm) | 0.01 ± 0.01 | 0.00 ± 0.00 | >0.05c |
a1percent level of significance ; b 5 percent level significance ; c not significant.
We observed a significant( p<0.01** ) difference in the total available carbohydrate between polished and unpolished barnyard millets at 1 % level of the significance which can be attributed to the higher level of total dietary fiber content (14.2 ± 0.28gm) of unpolished barnyard millets. Also since the quantum of the available amount of carbohydrate is directly proportional to the glycemic response, unpolished barnyard millets can be considered for incorporated in other cereals or as a healthy replacement for other cereals for the better dietary management of diabetes, obesity and cardiovascular diseases. Also except for maltose a significant difference in sucrose, glucose and fructose levels between polished and unpolished barnyard millets was observed at 99% or 95% confidence interval to indicate significance level.
Discussion
A significant difference in Crude fiber (p value <0.01**), Insoluble(p value<0.01**) ,soluble fiber ( p value <0.01**) and total dietary fiber( p-value <0.05*)was witnessed between polished and unpolished barnyard millets at 1 and 5% level of significance. Also, it was observed that the total fiber , the insoluble and soluble fiber content of unpolished barnyard millets were more or less similar to the total fiber, insoluble and soluble content of jowar (total fiber 10.22gm, insoluble,8.4gm and soluble 1.73gm) and wheat whole flour (total fiber 11.36gm, insoluble,9.7gm and soluble1.63 gm) as reported in nutritive value of Indian foods (IFCT-2017).17
The nutritious quality of milled barnyard millets at different moisture levels which showed a undesirably and linearly associated relationship with the grade of polishing,19 is concurrence with the difference in nutrient content observed between polished and unpolished barnyard millets in the present study. Thus the unpolished or whole barnyard millets can be a healthy replacement of carbohydrate and dietary fiber for patients with insulin insensitivity.
We found that the analyzed thiamine value of unpolished barnyard millet(0.45 ±0.04 mg) was greater than that of whole grains of jowar (0.35±0.04mg), ragi (0.37±0.04mg) and maize (0.33±0.03mg) and more or less same as that of wheat flour(0.42 ±0.04mg) and whole wheat(0.46 ±0.07mg) as stated in the nutritive value of Indian foods (IFCT-2017).17We also observed a higher amount of total folate in polished barnyard millet (69 ± 0.3 µg) and unpolished barnyard millet (78 ± 0.01 µg ). The iron content of barnyard millet both polished (6.2 ±0.02mg) and unpolished (7.1 ±0.11mg)was found to be higher compared to other millets except amaranth seed (8.02 ± 0.93 mg)and quinoa (7.5 mg ) . The analyzed value of iron content in barnyard millet reported in our study is similar to one estimated (6.91 mg/100 g) in another study in which nutritional and sensual feature of foxtail and barnyard millet foodstuffs with traditional rice products were compared. However in the present study we have also analyzed the iron content of unpolished barnyard millet which can serve as a nutrient source for future reference.
A significant upward trend (p ≤ 0.05) in the levels of tannins, lignins, phytic acid, alkaloids, and tocopherols were observed in polished barnyard millet in comparison to unpolished/whole millet. Also the quantum of tocopherols, alkaloids, and saponins present in both polished and unpolished barnyard millets was found to be inferior to the commonly consumed millets such as ragi (0.16 ±0.01mg) , jowar 0.36 ±0.3mg and cereals such as brown rice (0.69±0.12mg) and whole wheat flour (0.26 ±0.09mg). Furthermore no significant difference in Phytosterols, carotenoids, and saponins levels were observed between polished and unpolished barnyard millet. Henceforth, these variations in nutraceutical components call for future research on the extent of polishing barnyard millets to make it as a healthy nutritious choice for human consumption, especially for the diabetic population without compromising the nutraceutical potentials.
Conclusion
Both polished and unpolished barnyard millet was tested quantitatively for its nutritional and nutraceutical benefits, the results show that majority of the macro, micro, and nutraceutical components were more nutritionally superior in unpolished barnyard millet than polished one. Consumption of barnyard millets loaded with biologically active phytochemicals and nutraceutical compounds such as flavonoids, tannins, lignin, phenolic compounds, and other antioxidants can be encouraged to prevent and protect us from non-communicable lifestyle disorders and to nurture health society. Development of nutritious healthy millet replaced snacks, main dishes and accompaniment can not only add variety to the diet but can also serve as a healthy alternate for other staple cereals, particularly the rice. Thus as salient outcome , the present study on the nutritional quality of both polished and unpolished barnyard millet serve as an knowledge source of nutrient content for future scientific study.
Acknowledgement
The authors acknowledge Avinashilingam Institute for Home Science and Higher Education for Women for providing us the platform to conduct the research work.
Funding Source
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Conflict of Interest
The author(s) declares no conflict of interest. The Ethical clearance (Approval No-AUW/IHEC-17-18/FSMD/FHP-02) for the research work from Institutional Human Ethics Committee- Avinashilingam Institute for Home Science and Higher Education for Women was obtained.
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